In studies of deceased writers— based on their letters, medical records, and published biographies— and in studies of talented living writers, mental illness is prevalent. For example, fiction writers are fully ten times more likely to be bipolar than the general population, and poets are an amazing forty times more likely to struggle with the disorder. Based on statistics like these, psychologist Daniel Nettle writes, “It is hard to avoid the conclusion that most of the canon of Western culture was produced by people with a touch of madness.” Essayist Brooke Allen does Nettle one better: “The Western literary tradition, it seems, has been dominated by a sorry collection of alcoholics, compulsive gamblers, manic-depressives, sexual predators, and various unfortunate combinations of two, three…